Using physical and virtual functions associated with a NIC to access an external storage through network fabric driver

ABSTRACT

Some embodiments provide a method of providing distributed storage services to a host computer from a network interface card (NIC) of the host computer. At the NIC, the method accesses a set of one or more external storages operating outside of the host computer through a shared port of the NIC that is not only used to access the set of external storages but also for forwarding packets not related to an external storage. In some embodiments, the method accesses the external storage set by using a network fabric storage driver that employs a network fabric storage protocol to access the external storage set. The method presents the external storage as a local storage of the host computer to a set of programs executing on the host computer. In some embodiments, the method presents the local storage by using a storage emulation layer on the NIC to create a local storage construct that presents the set of external storages as a local storage of the host computer.

BACKGROUND

In recent years, there has been an increase in the use of hardwareoffload units to assist functions performed by programs executing onhost computers. Examples of such hardware offload units include FGPAs,GPUs, smart NICs, etc. Such hardware offload units have improvedperformance and efficiency requirements of the host computers byoffloading some of the operations that are typically performed by thehost computer CPU to the hardware offload unit.

BRIEF SUMMARY

Some embodiments of the invention provide a method of providingdistributed storage services to a host computer from a network interfacecard (NIC) of the host computer. At the NIC, the method accesses a setof one or more external storages operating outside of the host computerthrough a shared port of the NIC that is not only used to access the setof external storages but also for forwarding packets not related to theset of external storages or the distributed storage service. In someembodiments, the method accesses the external storage set by using anetwork fabric storage driver that employs a network fabric storageprotocol to access the external storage set.

The method in some embodiments presents the external storage as a localstorage of the host computer to a set of one or more programs executingon the host computer. In some embodiments, the local storage is avirtual disk, while the set of programs are a set of machines (e.g.,virtual machines or containers) executing on the host computer. In someembodiments, the method presents the local storage by using a storageemulation layer (e.g., a virtual disk layer) on the NIC to create alocal storage construct. In some embodiments, the emulated local storage(e.g., the virtual disk) does not represent any storage on the NIC,while in other embodiments, the emulated local storage also representsone or more storages on the NIC.

The method forwards read/write (R/W) requests to the set of externalstorages when receiving R/W requests from the set of programs to thevirtual disk, and provides responses to the R/W requests after receivingresponses from the set of external storages to the forwarded read/writerequests. In some embodiments, the method translates the R/W requestsfrom a first format for the local storage to a second format for the setof external storages before forwarding the requests to the externalstorage through the network fabric storage driver. The method alsotranslates responses to these requests from the second format to thefirst format before providing the responses to an NIC interface of thehost computer in order to provide these responses to the set ofprograms.

In some embodiments, the NIC interface is a PCIe (peripheral componentinterconnect express) interface, and the first format is an NVMe(non-volatile memory express) format. The second format in some of theseembodiments is an NVMeOF (NVME over fabric) format and the networkfabric storage driver is an NVMeOF driver. In other embodiments, thesecond format is a remote DSAN (distributed storage area network) formatand the network fabric storage driver is a remote DSAN driver. The NICin some embodiments includes a general purpose central processing unit(CPU) and a memory that stores a program (e.g., an NIC operating system)for execution by the CPU to access the set of external storages and topresent the set of external storages as a local storage. In someembodiments, the NIC also includes an application specific integratedcircuit (ASIC), which processes packets forwarded to and from the hostcomputer, with at least a portion of this processing including thetranslation of the R/W requests and responses to these requests. TheASIC in some embodiments is a hardware offload unit of the NIC.

In addition to providing an emulation layer that creates and presents anemulated local storage to the set of programs on the host, the method ofsome embodiments has the NIC execute a DSAN service for the localstorage to improve its operation and provide additional features forthis storage. One example of a DSAN service is the vSAN service offeredby VMware, Inc. The features of the DSAN service in some embodimentsinclude (1) data efficiency processes, such as deduplication operations,compression operations, and thin provisioning, (2) security processes,such as end-to-end encryption, and access control operations, (3) dataand life cycle management, such as storage vMotion, snapshot operations,snapshot schedules, cloning, disaster recovery, backup, long termstorage, (4) performance optimizing operations, such as QoS policies(e.g., max and/or min I/O regulating policies), and (5) analyticoperations, such as collecting performance metrics and usage data forvirtual disk (IO, latency, etc.).

These services are highly advantageous for improving performance,resiliency and security of the host's storage access that is facilitatedthrough the NIC. For instance, the set of host programs that access theemulated local storage do not have insight that data is being accessedon remote storages through network communications. Neither theseprograms nor other programs executing on the host in some embodimentsencrypt their storage access, as the storage being accessed appears tobe local to these programs. Hence, it is highly beneficial to use theDSAN services for the R/W requests and responses (e.g., its securityprocesses to encrypt the R/W requests and responses) exchanged betweenthe host and the set of external storages that are made to appear as thelocal storage.

The preceding Summary is intended to serve as a brief introduction tosome embodiments of the invention. It is not meant to be an introductionor overview of all inventive subject matter disclosed in this document.The Detailed Description that follows and the Drawings that are referredto in the Detailed Description will further describe the embodimentsdescribed in the Summary as well as other embodiments. Accordingly, tounderstand all the embodiments described by this document, a full reviewof the Summary, Detailed Description, the Drawings and the Claims isneeded. Moreover, the claimed subject matters are not to be limited bythe illustrative details in the Summary, Detailed Description and theDrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 illustrates one manner of using a smart NIC to emulate a localstorage that represents several external storages to a virtual machineexecuting over a hypervisor of a host computer.

FIG. 2 illustrates examples of adapters emulated by the smart NIC.

FIGS. 3 and 4 illustrate two different ways that a DSAN service on asmart NIC serves as a vSAN node in some embodiments.

FIGS. 5 and 6 illustrate two different ways that the smart NIC of someembodiments uses to translate between the NVMe and NVMeOF storageformats.

FIG. 7 illustrates a VM that executes on a smart NIC to implement thirdparty interface (protocols) that are needed to access a third partyexternal storage and that are not natively supported by the smart NIC orthe host.

FIG. 8 illustrates a process that some embodiments perform to handleegress communication from the host to a third party external storage.

FIG. 9 illustrates a process that some embodiments perform to handleingress communication from the third party external storage to the host.

FIG. 10 illustrates a smart NIC emulating a local storage using anexternal storage and a hardware offload unit driver.

FIG. 11 illustrates a process that the smart NIC OS performs in someembodiments to process an egress communication from the host to anexternal storage for the example illustrated in FIG. 10 .

FIG. 12 illustrates a process that the smart NIC OS performs in someembodiments to process an ingress packet from an external storage to thehost.

FIG. 13 illustrate one example of a smart NIC that is used with a hostto perform storage emulation.

FIG. 14 illustrates a process performed to process an egress NVMecommand by the smart NIC of FIG. 13 .

FIG. 15 illustrates another example of a smart NIC that is used with ahost to perform storage emulation.

FIG. 16 illustrates a process that is performed to process egresspackets from the VM.

FIG. 17 conceptually illustrates an electronic system with which someembodiments of the invention are implemented.

DETAILED DESCRIPTION

In the following detailed description of the invention, numerousdetails, examples, and embodiments of the invention are set forth anddescribed. However, it will be clear and apparent to one skilled in theart that the invention is not limited to the embodiments set forth andthat the invention may be practiced without some of the specific detailsand examples discussed.

Some embodiments of the invention provide a method of providingdistributed storage services to a host computer from a network interfacecard (NIC) of the host computer. At the NIC, the method accesses a setof one or more external storages operating outside of the host computerthrough a shared port of the NIC that is not only used to access the setof external storages but also for forwarding packets not related to theset of external storages or the distributed storage service. The NICsare sometimes referred to herein as smart NICs as they perform multipletypes of services and operations. In some embodiments, the methodaccesses the external storage set by using a network fabric storagedriver that employs a network fabric storage protocol (e.g., NVMeOF) toaccess the external storage set.

The method presents the external storage as a local storage of the hostcomputer to a set of programs executing on the host computer. In someembodiments, the local storage is a virtual disk, while the set ofprograms are a set of machines (e.g., virtual machines or containers)executing on the host computer. In some embodiments, the method presentsthe local storage by using a storage emulation layer (e.g., a virtualdisk layer) to create a local storage construct that presents the set ofexternal storages as a local storage of the host computer. In someembodiments, the emulated local storage (e.g., the virtual disk) doesnot represent any storage on the NIC, while in other embodiments, theemulated local storage also represents one or more storages on the NIC.

The method forwards read/write (R/W) requests to the set of externalstorages when receiving R/W requests from the set of programs to thevirtual disk, and provides responses to the R/W requests after receivingresponses from the set of external storages to the forwarded read/writerequests. In some embodiments, the method translates the R/W requestsfrom a first format for the local storage to a second format for the setof external storages before forwarding the requests to the externalstorage through the network fabric storage driver. The method alsotranslates responses to these requests from the second format to thefirst format before providing the responses to a NIC interface of thehost computer in order to provide these responses to the set ofprograms.

In some embodiments, the NIC interface is a PCIe interface, and thefirst format is an NVMe format. The second format in some of theseembodiments is an NVMeOF format and the network fabric storage driver isan NVMeOF driver. The NIC in some embodiments includes a general purposecentral processing unit (CPU) and a memory that stores a program (e.g.,an NIC operating system) for execution by the CPU to access the set ofexternal storages and to present the set of external storages as a localstorage. The NIC in some embodiments is implemented as a system on chip(SoC) with multiple other circuit components. For instance, in someembodiments, the NIC also includes an application specific integratedcircuit (ASIC), which processes packets forwarded to and from the hostcomputer, with at least a portion of this processing including thetranslation of the R/W requests and responses to these requests. ThisASIC in some embodiments is a hardware offload unit (HOU) of the NIC,and performs special operations (e.g., packet processing operations,response/request reformatting operations, etc.).

In addition to providing an emulation layer that creates and presents anemulated local storage to the set of programs on the host, the method ofsome embodiments has the NIC execute a distributed storage area network(DSAN) service for the local storage to improve its operation andprovide additional features for this storage. One example of a DSANservice is the vSAN service offered by VMware, Inc.

The DSAN services are highly advantageous for improving performance,resiliency and security of the host's storage access that is facilitatedthrough the NIC. For instance, the set of host programs that accessesthe emulated local storage does not have insight that data is beingaccessed on remote storages through network communications. Neitherthese programs nor other programs executing on the host in someembodiments encrypt their storage access, as the storage being accessedappears to be local to these programs. Hence, it is highly beneficial touse the DSAN services for the R/W requests and responses (e.g., itssecurity processes to encrypt the R/W requests and responses) exchangedbetween the host and the set of external storages that are made toappear as the local storage.

Although the description of some embodiments refers to emulations ofNVMe storage and NVMe storage protocol, in other embodiments otherstorage protocols may be emulated instead of or in addition to NVMestorages. Similarly, although the description refers to PCIe buses, inother embodiments, other system buses are used instead of or in additionto a PCIe bus. Although certain drivers and protocols are shown as beingused by external storages in various embodiments, other embodiments useother drivers or protocols for external storage. The smart NICsdescribed herein are described as having operating software. In someembodiments, this operating software is an operating system that hasdirect control over the smart NIC without an intervening program orhypervisor. In other embodiments, the operating software is a hypervisorthat runs on top of another operating system of the smart NIC. Stillother embodiments use just a hypervisor and no other operating system onthe smart NIC.

FIG. 1 illustrates one manner of using a smart NIC to emulate a localstorage 160 that represents several external storages 140 to one or morevirtual machines 112 executing over the operating system (OS) 100 of ahost computer. One example of such a machine is illustrated as a virtualmachine (VM) 112, which operates over a hypervisor 114 executing on thehost OS 100. The host computer has a set of processors that execute itsOS, hypervisor and VM. This computer also includes a smart NIC that hasa set of processors and a set of hardware offload units that assist inthe operation of the host computer. Specifically, in addition toperforming traditional NIC operations to forward packets to and from thehost computer (e.g., between the machines executing on the host computerand machines executing on other host computers), the smart NIC performsstorage emulation operations that represent multiple external storages140 as the local storage 160 to the machines executing on the hostcomputer. The smart NIC connects to PCIe bus 150 of the host.

The smart NIC in some embodiments is a system on chip (SoC) with a CPU,FPGA, memory, IO controller, a physical NIC, and other hardwarecomponents. The smart NIC has an operating system (OS) 120 that includesan NVMe driver 122 and a series of storage processing layers 124-127.The discussion below collectively refers to the software executing onthe smart NIC as the smart NIC OS 120. However, in some embodiments, thesmart NIC OS is a hypervisor, while in other embodiments a hypervisorexecutes on top of the smart NIC OS and some or all of the storageprocessing layers are part of this hypervisor. In the discussion below,the components that are attributed to the smart NIC OS 120 arecomponents of the hypervisor 114 that serves as the smart NIC OS orexecutes on top of the smart NIC OS in some embodiments. In otherembodiments, these are components of a smart NIC OS that is not ahypervisor. In still other embodiments, some of these components belongto the smart NIC OS, while other components belong to the hypervisorexecuting on the smart NIC OS.

The NVMe driver 122 is a driver for the PCIe bus 150. This driver relaysNVMe formatted R/W requests from the host hypervisor 114 to the storageprocessing layers, and relays responses to these requests from thestorage processing layers to the host hypervisor 114. The storageprocessing layers include an NVMeOF driver 124, a core storage service125, a DSAN service 126, and a virtual device service 127. The virtualdevice service includes an NVMe emulator 128.

The smart NIC OS 120 uses the NVMeOF driver 124 in some embodiments toaccess one or more external storages 140. Specifically, the smart NIC OS120 emulates a local NVMe storage 160 to represent several externalstorages 140 to the machines (e.g., VM 112) executing on the host. Fromthe host point of view, the VM 112 operates on the emulated localstorage 160 as if it was a local NVMe storage connected through the PCIebus 150.

To access the external storages 140, the smart NIC (e.g., the NVMeOFdriver) uses one or more of its shared ports 130. The shared ports arenot only used for the purposes of accessing external storage 140, butare also used for other purposes as well (e.g., used to forward packetsto and from destinations other than the external storages). The NVMeOFdriver 124 handles the NVMeOF protocols needed for communicating withthe external storages 140 through network fabric (e.g., throughrouters).

The smart NICs illustrated in FIG. 1 as well as in other figures performoperations other than storage emulation. For instance, the smart NICsperform regular packet processing in order to forward packets to andfrom other destinations outside of the smart NIC's host computer thatare not external storages. Examples of such other destinations includemachines executing on other host computers. However, the illustrationpresented in FIG. 1 and the other figures focus on the components of thesmart NIC that facilitate the storage emulation operations in order notto obscure the description of some embodiments with unnecessary detail.

The core storage service 125 provides one or more core storageoperations. One example of such operations are adapter services thatallow the smart NIC to emulate one or more storage adapters, with eachadapter logically connecting to one or more external storages 140 andfacilitating a different communication mechanism (e.g., transportmechanism) for communicating with the external storages. FIG. 2illustrates examples of such adapters. In this example, four adaptersare illustrated. These include an RDMA storage adapter, a TCP storageadapter, an iSCSI adapter, and an iSER adapter.

Through this interface, an administrator in some embodiments can specifyone or more adapters to use to access an external storage, or a set oftwo or more external storages. In some embodiments, more than oneadapter is specified for an external storage when the administratorwants to specify a multipath pluggable storage architecture (PSA)approach to accessing the storage. Once the administrator specifies anadapter, a network manager that provides the interface sends thedefinition of the specified adapter to a network controller, which thenconfigures the smart NIC to implement and configure a new driver, orreconfigure an existing driver, to access the external storage accordingto the adapter's specified definition. Different methods for configuringa smart NIC in some embodiments are described in concurrently filed U.S.patent application Ser. No. 17/145,318, entitled “Distributed StorageServices Supported by a NIC”, now published as U.S. Patent Publication2022/0100432, which is incorporated herein by reference.

The DSAN service 126 provides one or more DSAN operations to improve theoperation of the emulated local storage 160 and provide additionalfeatures for this storage. These operations are performed as theemulated local storage is not really local but rather an emulation ofone or more external storages. As such, the DSAN service 126 addressesone or more things that can go wrong in accessing such a virtual “local”storage.

For instance, in some embodiments, the DSAN service provides dataresiliency and I/O control that are not generally needed when a hostmachine is accessing a physical local storage over NVMe. A local driveis not subject to interception over a network and is not prone to packetduplication in the manner of packets sent over a network. These issuesarise from emulating the local storage using external storage accessedover a network, therefore the DSAN layer 126 resolves such issues beforethe data is presented to the higher layers.

In some embodiments, the DSAN operations include (1) data efficiencyprocesses, such as deduplication operations, compression operations, andthin provisioning. (2) security processes, such as end-to-endencryption, and access control operations, (3) data and life cyclemanagement, such as storage vMotion, snapshot operations, snapshotschedules, cloning, disaster recovery, backup, long term storage, (4)performance optimizing operations, such as QoS policies (e.g., maxand/or min I/O regulating policies), and (5) analytic operations, suchas collecting performance metrics and usage data for virtual disk (IO,latency, etc.).

One example of a DSAN service 126 is the vSAN service offered by VMware,Inc. In some such embodiments, the smart NIC includes a local physicalstorage that can serve as a vSAN storage node. In other embodiments, thesmart NIC does not have a local physical storage, or has such a storagebut this data storage cannot participate as a vSAN storage node. In suchembodiments, the smart NIC serves as a remote vSAN client node, and itsvSAN layer is a vSAN proxy that uses one or more remote vSAN nodes thatperform some or all of the vSAN operations and then direct the vSANproxy what to do.

FIG. 3 illustrates such an approach. As shown, the vSAN proxy 326 uses aremote vSAN client protocol to communicate with the other vSAN nodes305, which direct the vSAN operations of the vSAN proxy. The vSAN nodes305 provide some or all of the external storages 140 in some embodimentsof the invention. In this example, the network storage driver 324 is aniSCSI driver, although other network storage drivers are used in otherembodiments.

In other embodiments, the DSAN service of the smart NIC does not use aremote vSAN client protocol to communicate with the other vSAN nodes.For instance, as shown in FIG. 4 , a DSAN service 126 in someembodiments uses a vSAN over NVMeOF protocol 426 to communicate with theother vSAN nodes. This protocol is defined in some embodiments to allowthe smart NIC to be a vSAN node that does not have a local physicalstorage, or has such a storage but this data storage cannot participateas a vSAN storage node. In some embodiments, the emulated local storage160 (that is defined by one or more external storages 140 throughemulation operations of the NVMe emulator 128 of the virtual deviceservice 127 of the smart NIC OS 120) serves as the local storage thatallows the smart NIC to be a vSAN node.

The virtual device service 127 has an NVMe emulator 128 that emulatesthe local NVMe storage 160 to represent the set of external storages 140that are accessed through the NVMeOF driver 124 and the interveningnetwork. As part of this emulation, the virtual device layer 127 mapsoutgoing NVMe access commands to external storage access commands, andthe incoming external storage responses to an NVMe memory response. Whenmultiple external storages are used, this mapping involves mappingbetween a storage location in the emulated local storage 160 and astorage location in one or more external storages 140. One example of avirtual device emulator that can be used for the NVMe emulator is thevirtual device emulator of the vSphere software of VMware, Inc.

Part of the NVMe emulator's operation also involves this emulator usingthe hardware offload unit (e.g., an ASIC) of the smart NIC to convertthe NVMe access commands from an NVMe-PCIe format to an NVMe format, andto convert the external storage responses received at the emulator 128from the NVMe format to an NVMe-PCIe format (e.g., to remove PCIe headerinformation from outgoing commands, and to add PCIe header informationto incoming responses). This is further described below by reference toFIGS. 5 and 6 .

The host OS 100, the hypervisor 114 or the VM 112 in some embodimentshave their own drivers (not shown) for sending and receiving datathrough the PCIe bus 150. The host OS 100, the hypervisor 114 or the VM112 treats the virtual local storage 160 as a physical local storage,without having to deal with the operations that the smart NIC performsto send data to and receive data from the set of external storages 140.

DSAN services 126 (such as the remote DSAN client of FIG. 3 or the vSANover NVMeOF of FIG. 4 ) are two ways of offering disaggregated storageservices. Today, many DSANs (e.g., VMware's vSAN architecture) are partof a hyper-converged solution, in which each vSAN node offers bothstorage and compute functionality. As illustrated by FIGS. 3 and 4 ,disaggregated storage in some embodiments refers to storage in a systemwhich has some DSAN nodes (e.g., some hardware boxes) that provide onlycompute functionality and no storage functionality. In some embodiments,one or more DSAN nodes only offer storage functionality and no computefunctionality. Such a disaggregated system allows more flexibility indatacenters by allowing the operators of the datacenters to add morestorage boxes than compute boxes or more compute boxes than storageboxes, whichever is necessary, rather than adding additional computeboxes with storages whenever additional capacity of only one of thoseresources is necessary.

FIGS. 5 and 6 illustrate two different ways that the smart NIC of someembodiments uses to translate between the NVMe and NVMe-PCIe formats(e.g., to remove PCIe header from outgoing storage access commands andto add PCIe header information to incoming storage responses). Both ofthese techniques use a hardware offload unit (HOU) 505 of the smart NICto perform these operations. This HOU is an ASIC that has multiplepacket processing stages that can be configured to remove or add PCIeheaders to storage commands and responses to and from the externalstorages. In both approaches illustrated in FIGS. 5 and 6 , the NVMeemulator 128 uses an HOU interface 520 to communicate with the HOU 505.

In FIG. 5 , the HOU interface executes on a VM 510 that executes on thesmart NIC. The smart NIC OS is a hypervisor and the VM 510 executes ontop of this hypervisor in some embodiments. As shown, the NVMe emulator528 of the virtual device layer 527 communicates with the HOU interface520 to forward storage access commands and responses for processing bythe HOU 505 and to receive processed commands and responses from the HOU505. In other embodiments, the smart NIC executes the HOU interface onmachines (e.g., Pods or containers) other than VMs. One example of anHOU interface and the HOU are the Snap software and hardware offered byNvidia, Inc. In some embodiments, the HOU Snap software operates on theVM as it requires a different OS (e.g., require Ubuntu) than the smartNIC OS (which might be ESX offered by VMware, Inc.).

In some embodiments, a smart NIC is able to employ HOU drivers that areadapted to the smart NIC OS (e.g., HOU drivers supplied along with thesmart NIC operating software or subsequently downloaded, etc.) as theinterface with the smart NIC HOU. The HOU drivers that are adapted torun directly on a particular type of operating software are referred toas being “native” to that operating software. In FIG. 6 , the HOUinterface 520 is implemented as a native HOU driver 610 of the smartNIC. This approach works when the driver is available natively for thesmart NIC OS. Otherwise, the driver has to operate in a VM 510 as inFIG. 5 .

More generally, a VM is used by the smart NIC of some embodiments toperform other processes and/or support other protocols that are notnatively supported by the smart NIC in some embodiments. For instance,FIG. 7 illustrates a VM 710 that executes on a smart NIC OS 700 toimplement third party interface 725 (e.g., third party storage protocol)that is needed to access a third party external storage 712 and that isnot natively provided by the smart NIC OS or the host OS. In thisexample, the third party storage interface 725 is part of an interface520 for a HOU 715 of the smartNIC.

At the direction of the HOU interface 520 (also called the HOU handler),the HOU 715 performs storage command and response processing operationsneeded to implement the third party storage protocol and to convertbetween the command and response formats of the host's local storage(e.g., its NVMe local storage) and the third party external storage 712.As shown, the third party storage interface 725 passes storage accesscommands and receives storage access responses from a shared port 720 ofthe NIC.

FIG. 8 illustrates a process 800 that some embodiments perform to handleegress communication from the host to a third party external storage. Asshown, the process 800 starts (at 805) when a workload VM or anapplication running on the host generates an NVMe command (with data).At 810, the NVMe command is then encapsulated into a PCI-NVME command(i.e., encapsulated with a PCIe header) at a local storage controller ofthe host computer, and is forwarded along the PCIe bus to the smart NIC700. At the smart NIC 700, the PCI-NVMe command is passed (at 815) tothe HOU handler 520 running inside of the VM 710.

Next, at 820, the third party storage interface 725 strips off the PCIHeaders and passes NVMe command back to the HOU handler 520. To do this,the third party storage interface 725 uses the HOU in some embodiments.The HOU handler next uses (at 825) the smart NIC HOU to change theformat of the NVMe command to a command that comports with the thirdparty storage 712, and passes (at 830) this command to the third partystorage 712 along a shared port of the smart NIC. In some embodiments,the command is passed to the third party storage 712 as one or morepackets transmitted through the network fabric.

FIG. 9 illustrates a process 900 that some embodiments perform to handleingress communication from the third party external storage to the host.As shown, the process 900 starts (at 905) when it gets a storage-accessresponse (e.g., a Read response) through a shared port of the NIC fromthe third party external storage 712. At 910, the smart NIC OSdetermines that the storage-access response is from a third partyexternal storage that needs to be processed by the third party storageinterface 725 of the HOU handler 520.

At 915, the HOU Interface 520 gets the storage-access response andprovides it to the third party storage interface 725, which thenconverts (at 920) the storage-access response from a third party formatto an NVMe format and passes the storage-access response back to the HOUinterface 520. Next, at 925, the HOU interface encapsulates the NVMestorage-access response with a PCIe header, and is passed to the host'slocal storage controller along the PCIe bus 150. The local storagecontroller then removes (at 930) the PCIe header, and provides the NVMestorage-access response to a workload VM or an application running onthe host.

As described with respect to FIG. 1 , the smart NICs of some embodimentsprovide a DSAN service to perform various security and efficiencyoperations for the virtual local storage that is emulated with one ormore external storages. However, the smart NIC in other embodimentsbypasses the DSAN layer that performs DSAN operations in order toincrease the speed of data transfer. Instead of the HOU driversdescribed above, some such embodiments use other protocols. For example,some embodiments use HOU upper level protocols (ULP). Upper levelprotocols (e.g., IPoIB, SRP, SDP, iSER, etc.) facilitate standard datanetworking, storage and file system applications to operate overInfiniBand.

FIG. 10 illustrates a smart NIC emulating a local storage for the VMs112 of a host 1000 by using an external storage 1040 and a HOU driver1022. Like the above-described HOU interfaces and drivers, the HOUdriver 1022 forwards data messages for processing by the smart NIC HOU505 and receives processed data messages from the HOU 505. Specifically,the HOU driver 1022 uses the HOU 505 to perform the packet processingneeded to convert between the data message NVMe formats and the NVMePCIe formats. In this example, the HOU driver 1022 exchanges datamessages with a kernel NVMe layer 1028, which exchanges data messageswith an NVMe RDMA driver 1024 and/or an NVMe TCP driver 1026. The NVMeRDMA and TCP drivers send and receive data messages to and from externalstorage 1040 through an intervening network fabric (e.g., interveningrouters and switches).

One advantage of the approach of FIG. 10 is that the smart NIC 1020transfers data quickly between the host and the external storage 1040that is used to emulate the host's local storage 1020. This transfer isfast because it uses the kernel NVMe 1028 as a bridge and it does notuse a DSAN layer 1030 on the smart NIC OS 1020. This embodiment can tapinto NVMe RDMA offload capability by using the NVMe RDMA driver 1024. Insome embodiments, the HOU of the smart NIC 1020 can strip Ethernetheaders from an incoming data packet, identify the particular NVMe PCIecontroller (here, the HOU ULP driver 1022) that needs to receive thepacket, and pass the packet to that NVMe PCIe controller. Thus, thesmart NIC CPU cost of bridging through the kernel NVMe layer 1028 isminimal. This speed comes at a cost of other features, such as bypassingthe DSAN service 1030 which provides useful security and performanceoperations for the emulated local storage.

In the example of FIG. 10 , the DSAN module 1056, the virtual deviceemulator 1057 and the multipath PSA service 1055 are provided for one ormore VMs 112 through the host hypervisor 114. Specifically, in thisexample, a multipath PSA layer 1055 exists between the VMs 112 executingon the host OS 1000 and the NVMe PCIe driver 1060 of the OS. Throughthis PSA layer 1055, the host can use multiple paths to the sameexternal storage by using different NVMe PCIe drivers executing on thehost OS 1000 (although only one NVMe PCIe driver 1060 is shown in FIG.10 ). In other words, for the multi-pathing, different PCIe drivers arealso used in some embodiments to access the same external storagethrough different paths. Also, in some embodiments, the different NVMePCIe drivers are used to emulate different local storages from differentexternal storages 1040.

The virtual device emulator 1057 is used to emulate a local virtual diskfrom several external storages 1040 for one or more VMs 112. Asmentioned above, the vSphere software's virtual device layer is used toimplement the virtual device emulator of the host hypervisor or smartNIC hypervisor in some embodiments. In some embodiments, the same ordifferent PCIe drivers 1060 are used to access different externalstorages 1040 that are used to emulate one virtual disk. The DSAN module1056 performs DSAN services like those described above for the emulatedlocal storages.

In some embodiments, the host hypervisor and smart NIC hypervisor can beconfigured to provide different storage services for different workloadVMs 112. For instance, the storage access commands and responses for oneworkload VM is processed by the storage services 1055-57, while thestorage access commands and responses for another workload VM skip thesestorage services. Similarly, the storage access commands and responsesof one workload VM is processed by the storage services 125-127 of thesmart NIC as shown in FIG. 1 , while the storage access commands andresponses of another workload VM are just processed by the kernel NVMemodule 1028 and NVMeOF drivers 1024 and 1026 of FIG. 10 .

FIG. 11 illustrates a process 1100 that the smart NIC OS 1020 performsin some embodiments to process an egress communication from the host toan external storage for the example illustrated in FIG. 10 . As shown,the process starts (at 1105) when an NVMe command (with data) isgenerated by a VM 112 on the host. This packet (at 1110) is encapsulatedwith PCIe header information to produce a PCIe-NVMe command (with data)at a local storage controller (not shown) of the host, and is passedalong to the PCIe bus 150. Next, at 1115, the HOU driver 1022 (e.g., HOUULP driver) receives this command through the PCIe bus 150, and uses theHOU to strip out the PCI headers and produce the NVMe command (withdata).

At 1120, the HOU driver 1022 passes the NVMe command to the kernel NVMemodule 1028, which maps this packet to an NVMeOF transport controller.The kernel NVMe module 1028 in some embodiments is transport agnostic,and can be configured to use any one of a number of different NVMetransport drivers. At 1120, the kernel NVMe 1028 identifies the NVMeOFcontroller (i.e., NVMe RDMA controller 1024 or NVMe TCP controller 1026)that needs to receive this NVMe command. This identification is based onthe NVMe command parameters that identify the transport protocol to use.These command parameters are provided by the host's multipath PSA layer1055.

The kernel module (at 1125) passes the NVMe command to the identifiedNVMeOF controller, which then generates one or more NVMeOF packets toforward (at 1130) the NVMe command to the destination external storagethrough a shared port of the smart NIC. As mentioned above, both NVMeRDMA 1024 and NVMe TCP 1026 are provided by the smart NIC OS 1020 foraccessing remote external storages 1040 through the shared port(s) 130of the smart NIC. In some embodiments, the kernel NVMe 1028 works like amultiplexer that provides NVMe storage access to the HOU driver 1022using different transports, such as NVMe RDMA 1024 and NVMe TCP 1026, atthe same time. After 1130, the process 1100 ends.

FIG. 12 illustrates a process 1200 that the smart NIC OS 1020 performsin some embodiments to process an ingress packet from an externalstorage to the host. As shown, the process starts (at 1205) when anexternal storage 1040 generates and forwards an NVMeOF command (withdata) that is received as a set of one or more network packets at ashared port of the smart NIC through network fabric (e.g., through oneor more switches and/or routers). The port (at 1210) passes the receivedpacket to the NVMe RDMA controller 1024 or NVMe TCP controller 1026depending on the transport protocol used by the external storage. TheNVMe controller (at 1215) receives the NVMeOF packet in its transportspecific format, removes the transport header data, and provides an NVMecommand (with data) to the kernel NVMe 1028.

At 1220, the kernel NVMe 1028 maps the received NVMe command to the HOUdriver 1022 as the NVMe command needs to go to host. In someembodiments, the kernel NVMe 1028 creates a record when it wasprocessing an egress packet at 1125 and uses this record to perform itsmapping at 1220. In some embodiments, the kernel NVMe 1028 provides theNVMe command to the HOU driver 1022 with the controller of the emulatedlocal storage 160 as the command's destination. At 1225, the HOU driver1022 then encapsulates the NVMe command with a PCIe header by using thesmart NIC's HOU and then sends the NVMe command along the host PCIe tothe local storage controller of the emulated local storage 160. The hostPCIe then provides (at 1230) the NVMe command to the local storagecontroller through the NVMe PCIe driver 1060. This controller thenremoves (at 1230) the PCIe header and provides the NVMe command to thedestination VM 112. The process 1200 then ends.

In some embodiments, the smart NICs are used as storage accessaccelerators. FIGS. 13 and 15 illustrate two such examples. FIG. 13illustrates how a smart NIC serves as a network accelerator to one ormore workload VMs 1312 executing over a host hypervisor 1314 thatoperates over a host OS 1300. In this example, the remote storageservices protocol is running inside the host and the smart NIC OS 1320just runs network accelerators. Also, the host hypervisor 1314 providesemulation services in this example that allow it to present one or moreexternal storages 1340 as a local storage to a VM 1312. In someembodiments, the hypervisor 1314 is the ESX hypervisor of VMware, Inc.In some such embodiments, a virtual NVMe device emulation module 1311 ofthe VMware vSphere software provides the NVMe device emulation thatpresents multiple external storages 1340 as a single local NVMe storageto the VM 1312.

In some embodiments, the hypervisor 1314 also includes the DSAN servicelayer 1313, which provide distributed storage services for the emulatedlocal NVMe storage. As mentioned above, the distributed storage servicesin some embodiments account for the VM 1312 having no knowledgeregarding the plurality of external storages being used to emulate thelocal storage. These DSAN service improve this emulated storage'soperation and provide additional features for it. Examples of suchfeatures in some embodiments include (1) data efficiency processes, suchas deduplication operations, compression operations, and thinprovisioning, (2) security processes, such as end-to-end encryption, andaccess control operations, (3) data and life cycle management, such asstorage vMotion, snapshot operations, snapshot schedules, cloning,disaster recovery, backup, long term storage, (4) performance optimizingoperations, such as QoS policies (e.g., max and/or min I/O regulatingpolicies), and (5) analytic operations, such as collecting performancemetrics and usage data for virtual disk (IO, latency, etc.) One exampleof a DSAN service is the vSAN service offered by VMware vSpheresoftware. The DSAN service layer 1313 also includes a multipathing PSAlayer in some embodiments.

The DSAN service module 1313 receives and sends storage related NVMecommands from and to the kernel NVMe module 1315. The kernel NVMe module1315 interacts with either the NVMe RDMA driver 1316 or NVMe TCP driver1317 to receive and send these NVMe commands. These drivers exchangethese NVMe commands with the smart NIC OS 1320 through one or morevirtual functions (VFs) 1322 defined for these drivers on the smart NICOS.

In some embodiments, the smart NIC OS can present the smart NIC asmultiple physical functions (PF) connected to the host computer. ThePCIe bus 150, in some embodiments, allows for the creation of these PFs.A PF, in some embodiments, can be further virtualized as multiplevirtual functions (VFs). More specifically, in some embodiments,physical functions and virtual functions refer to ports exposed by asmart NIC using a PCIe interface to connect to the host computer overthe PCIe bus. A PF refers to an interface of the smart NIC that isrecognized as a unique resource with a separately configurable PCIeinterface (e.g., separate from other PFs on a same smart NIC). In someembodiments, each PF is executed by the processing units (e.g.,microprocessors) of the host computer.

The VF refers to a virtualized interface that is not fully configurableas a separate PCIe resource, but instead inherits some configurationfrom the PF with which it is associated while presenting a simplifiedconfiguration space. VFs are provided, in some embodiments, to provide apassthrough mechanism that allows compute nodes executing on a hostcomputer to receive data messages from the smart NIC without traversinga virtual switch of the host computer. The VFs, in some embodiments, areprovided by virtualization software executing on the smart NIC. In someembodiments, each VF is executed by the processing units (e.g.,microprocessors) of the smart NIC.

The VFs and PFs, in some embodiments, are deployed to support storageand compute virtualization modules. For example, a PF or VF can bedeployed to present a storage or compute resource provided by the smartNIC as a local device (i.e., a device connected to the host computer bya PCIe bus). Defining such VFs are further described in the concurrentlyfiled, above incorporated U.S. patent application Ser. No. 17/145,318,entitled “Distributed Storage Services Supported by a NIC” and nowpublished as U.S. Patent Publication 2022/0100432.

The PF 1370 on the host has the corresponding VF 1322 on the smart NIC.The PF 1370 represents a shared NIC port to the NVMeOF drivers 1316 and1317, which run on the host and convert the NVMe storage access commandsto network packets. These drivers use this representative port 1370 toforward storage access packets to an external storage through the VF1322 of the smart NIC 1320, and to receive storage access responsepackets from the external storage 1340 through the VF 1322 of the smartNIC 1320.

When the VF 1322 does not know how to process a packet (e.g., when itreceives a first packet of a new flow for which it does not have aforwarding rule), the VF passes the packet through a “slow-path” thatincludes the virtual switch 1326 of the virtualization layer 1327, whichthen determines how to forward the packet and provides the VF withforwarding rule for forwarding the packet. On the other hand, when theVF 1322 knows how to process a packet (e.g., when the VF receivesanother packet of a flow that it has previously processed and/or forwhich it has a forwarding rule), the VF passes the packet through a“fast-path,” e.g., passes a packet of a previously processed flowdirectly to the NIC driver 1325 for forwarding to an external storage1340. Accordingly, in the example illustrated in FIG. 13 , the VF 1322is a network accelerator that facilitates the forwarding of the packetsrelated to the external storages.

In some embodiments, the VF 1322 uses the smart NIC HOU 505 to performits fast path forwarding. When the HOU is not programmed withflow-processing rules needed to process a new flow, the VF 1322 in someembodiments passes the packet to the virtualization layer 1327, whicheither identifies the flow-processing rule for a rule cache or passesthe packet to a manager (executing on the smart NIC or on an externalcomputer) that then determines the flow processing rule, and passes thisrule back to the virtualization layer to use to forward the packet andto program the HOU. Once programmed, the VF can use the HOU to processsubsequent packets of this flow.

FIG. 14 illustrates a process 1400 performed to process an egress NVMecommand by the smart NIC 1320 of FIG. 13 . In this example, the VM 1312is presented an NVMe device through a virtual NVMe device emulationprovided by the hypervisor 1314 (e.g., provided by a virtual NVMe deviceemulation module of the vSphere software of VMware Inc.). The NVMedevice present in VM 1312 generates (at 1405) an NVMe command (withdata). The VM's NVMe driver passes (at 1410) this NVMe command throughthe virtual device layer 1311 and the DSAN service layer 1313, to thekernel NVMe module 1315. At 1415, the kernel NVMe module 1315 identifiesthe NVMeOF controller that needs to process this NVMe command, andprovides the packet to this controller 1316 or 1317.

The NVMEoRDMA 1316 or NVMEoTCP 1317 module running on the host (at 1420)converts the NVMe command to one or more NVMe network packets (NVMeOFpackets) and passes the packets to a PF 1370 of the PCIe bus 150. At1425, the PF 1370 adds PCIe header information to the NVMe networkpackets, and then passes the packets along the PCIe bus 150. The PCIebus 150 creates a mapping between the PF 1370 and the VF module 1322running on the smart NIC. Hence, the VF module 1322 receives each NVMeOFpacket through the PCIe bus 150.

At 1430, the VFI module 1322 then transfers the NVMeOF packet eitherdirectly through the fast path to the NIC driver 1325, or indirectly tothe NIC driver 1325 through the slow path that involves the virtualswitch 1326. The NIC driver 1325 then forwards the NVMeOF packet througha shared port of the smart NIC, so that this packet can be forwardedthrough intervening network fabric (e.g., intervening switches/routers)to reach its destination external storage 1340. In some embodiments, thefast-path processing of the VF 1322 allows the VF to directly pass thepacket to the shared port of the smart NIC. The process then ends.

FIG. 15 illustrates another way of using the smart NIC as a networkaccelerator in some embodiments. In this example, one VM 1512 executesthe NVMeOF driver, so that it cannot only bypass the DSAN service layer1313, but also the kernel NVMe 1315 and NVMeOF drivers 1316-17 of thehost hypervisor 1514 that executes over a host OS 1500. This approachprovides the fastest access for a VM to one or more external storagesthrough the VM's NVMeOF driver, which in this example is a GOS NVMefabric driver. However, in this approach, no local storage is emulatedfor the VM 1514 by either the host or the smart NIC. This VM simplyaccesses the external storages through its NVMeOF driver. Specifically,in the example of FIG. 15 , the GOS NVMeOF driver inside the VM 1512presents the NVMe device to the VM 1512. Also, a PF 1580 is directlyassigned to VM 1512 using a passthrough mode, such as SRIOV Mode or SIOVMode.

For the PF 1580, the smart NIC OS in FIG. 15 defines a VF 1523 toprocess the packets associated with the VM 1514. In both FIGS. 13 and 15, the smart NIC OS has a virtual switch 1326 to perform softwareswitching operations and a network virtualization 1327 layer to performnetwork virtualization operations for the smart NIC. In someembodiments, these operations are analogous to the operations thattraditionally have been performed on host computers to provide softwareswitching and network virtualization operations. The smart NIC OS 1320also has a NIC driver 1325 to communicate with the external storages1340 through one or more ports of the smart NIC.

FIG. 16 illustrates a process 1600 that is performed to process egresspackets from the VM 1512. As shown, the process starts (at 1605) when anapplication running on the VM 1512 generates an NVMe command (withdata), and provides this command to the NVMeOF driver executing on thisVM. This driver then coverts (at 1610) the NVMe command to a set of oneor more network packets, which it then provides to the PF 1580 directly.

The PF 1580 provides (at 1615) the set of network packets that containsthe NVMe command (with data) to the VF2 1523, which is a high speednetwork adapter provided by the smart NIC 1320. As described above forVF 1322 and operation 1430 of FIG. 14 , the VF2 1523 (at 1620) transfersthe set of network packets (containing the NVMe command/data) throughthe direct fast path or the indirect slow path, to a shared NIC port forforwarding to an external storage 1340. In some embodiments, the sharedNIC port can be used by both VFs 1322 and 1523 as well as other modulesof the smart NIC for other forwarding operations.

The smart NIC operating system in some embodiments is provided with thehost-computer hypervisor program as part of a single downloaded package.For instance, some embodiments provide a method for provisioning a smartNIC with a smart NIC operating system for enabling resource sharing onthe smart NIC connected to a host computer. The method, in someembodiments, is performed by the host computer and begins when the hostcomputer receives (1) a host-computer hypervisor program for enablingresource sharing on the host computer and (2) the smart NIC operatingsystem. In some embodiments, the host-computer hypervisor programincludes the smart NIC hypervisor program. The host computer theninstalls the host-computer hypervisor program and provides the smart NICoperating system to the smart NIC for the smart NIC to install on thesmart NIC. One of ordinary skill in the art will appreciate that ahypervisor program is used as an example of virtualization software(e.g., software enabling resource sharing for a device executing thesoftware).

The smart NIC, in some embodiments, is a NIC that includes (i) anapplication-specific integrated circuit (ASIC), (ii) a general purposecentral processing unit (CPU), and (iii) memory. The ASIC, in someembodiments, is an I/O ASIC that handles the processing of packetsforwarded to and from the computer and is at least partly controlled bythe CPU. The CPU executes a NIC operating system in some embodimentsthat controls the ASIC and can run other programs, such as APItranslation logic to enable the compute manager to communicate with abare metal computer. The smart NIC also includes a configurableperipheral control interconnect express (PCIe) interface in order toconnect to the other physical components of the bare metal computersystem (e.g., the x86 CPU, memory, etc.). Via this configurable PCIeinterface, the smart NIC can present itself to the bare metal computersystem as a multitude of devices, including a packet processing NIC, ahard disk (using non-volatile memory express (NVMe) over PCIe), or otherdevices.

Although not necessary for managing a bare metal computer, the NICoperating system of some embodiments is capable of executing avirtualization program (similar to a hypervisor) that enables sharingresources (e.g., memory, CPU resources) of the smart NIC among multiplemachines (e.g., VMs) if those VMs execute on the computer. Thevirtualization program can provide compute virtualization servicesand/or network virtualization services similar to a managed hypervisor.These network virtualization services, in some embodiments, includesegregating data messages into different private (e.g., overlay)networks that are defined over the physical network (shared between theprivate networks), forwarding the data messages for these privatenetworks (e.g., performing switching and/or routing operations), and/orperforming middlebox services for the private networks.

The host-computer hypervisor program and the smart NIC operating system,in some embodiments, are programs that do not have previous versionsinstalled on the computer or the smart NIC. In other embodiments, thehost-computer hypervisor program and the smart NIC operating systemreceived by the host computer are update programs for previouslyinstalled versions of the host-computer hypervisor program and the smartNIC operating system. After a host-computer hypervisor program and thesmart NIC operating system are received, the host computer, in someembodiments, receives an additional program for updating the smart NICoperating system and provides the received program to the smart NIC forthe smart NIC to update the smart NIC operating system.

In some embodiments, after receiving the host-computer hypervisorprogram and the smart NIC operating system, the host computer detects(or determines) that the host computer is connected to the smart NIC. Insome embodiments, the connection is made over a standard PCIe connectionand the smart NIC is detected as a peripheral device that supports theinstallation of the smart NIC operating system. The host computerprovides, based on the detection, the smart NIC operating system to thesmart NIC for the smart NIC to install. In some embodiments, the smartNIC operating system is sent to the smart NIC along with an instructionto the smart NIC to install the smart NIC operating system.

In some embodiments, the host computer includes a local controller thatreceives the host-computer hypervisor program and the smart NICoperating system. The local controller, in some embodiments, providesthe host-computer hypervisor program and the smart NIC operating systemto a compute agent that installs the host-computer hypervisor program onthe host computer to enable the host computer to share resources among aset of compute nodes (e.g., virtual machines, containers, Pods, etc.).The host-computer hypervisor program and the smart NIC operating systemare particular examples of virtualization software that is used, in someembodiments, to enabling resource sharing for the host computer andsmart NIC, respectively.

As mentioned above, the smart NIC in some embodiments includes a set ofASICs, a general purpose CPU, and a memory. The set of ASICs, in someembodiments, includes an ASIC for processing packets forwarded to andfrom the host computer as well as other ASICs for acceleratingoperations performed by the smart NIC on behalf of the host computer(e.g., encryption, decryption, storage, security, etc.). The smart NICoperating system, in some embodiments, includes virtualization programsfor network virtualization, compute virtualization, and storagevirtualization. The virtualization programs, in some embodiments, enablesharing the resources of the smart NIC among multiple tenants of amulti-tenant datacenter.

The network virtualization program provides network virtualizationservices on the smart NIC. The network virtualization services, in someembodiments, include forwarding operations (e.g., network switchingoperations and network routing operations). The forwarding operationsare performed, in some embodiments, on behalf of multiple logicallyseparate networks implemented over a shared network of a datacenter.Forwarding packets for different logical networks, in some embodiments,includes segregating packets for each logically separate network intothe different logically separate networks. Forwarding operations for thedifferent logical networks, in some embodiments, are implemented asdifferent processing pipelines that perform different sets ofoperations. The different sets of operations include, in someembodiments, different logical packet forwarding operations (e.g.,logical switching, logical routing, logical bridging, etc.) anddifferent middlebox services (e.g., a firewall service, a load balancingservice, etc.).

The compute virtualization program, in some embodiments, providesvirtualized compute resources (virtual machines, containers, Pods, etc.)that execute over the compute virtualization program. The storagevirtualization program, in some embodiments, provides storagevirtualization services on the smart NIC. The virtualized storage, insome embodiments, include one or multiple of virtual storage areanetworks (vSANs), virtual volumes (vVOLs), and other virtualized storagesolutions. The virtualized storage appears to the connected hostcomputer as a local storage, in some embodiments, even when the physicalresources that are the backend of the virtualized storage are providedby a distributed set of storages of multiple physical host computers.

FIG. 17 conceptually illustrates an electronic system 1700 with whichsome embodiments of the invention are implemented. The electronic system1700 can be used to execute any of the control, virtualization, oroperating system applications described above. The electronic system1700 may be a computer (e.g., a desktop computer, personal computer,tablet computer, server computer, mainframe, a blade computer etc.),phone, PDA, or any other sort of electronic device. Such an electronicsystem includes various types of computer readable media and interfacesfor various other types of computer readable media. Electronic system1700 includes a bus 1705, processing unit(s) 1710, a system memory 1725,a read-only memory 1730, a permanent storage device 1735, input devices1740, and output devices 1745.

The bus 1705 collectively represents all system, peripheral, and chipsetbuses that communicatively connect the numerous internal devices of theelectronic system 1700. For instance, the bus 1705 communicativelyconnects the processing unit(s) 1710 with the read-only memory 1730, thesystem memory 1725, and the permanent storage device 1735.

From these various memory units, the processing unit(s) 1710 retrieveinstructions to execute and data to process in order to execute theprocesses of the invention. The processing unit(s) may be a singleprocessor or a multi-core processor in different embodiments.

The read-only-memory (ROM) 1730 stores static data and instructions thatare needed by the processing unit(s) 1710 and other modules of theelectronic system. The permanent storage device 1735, on the other hand,is a read-and-write memory device. This device is a non-volatile memoryunit that stores instructions and data even when the electronic system1700 is off. Some embodiments of the invention use a mass-storage device(such as a magnetic or optical disk and its corresponding disk drive) asthe permanent storage device 1735.

Other embodiments use a removable storage device (such as a floppy disk,flash drive, etc.) as the permanent storage device. Like the permanentstorage device 1735, the system memory 1725 is a read-and-write memorydevice. However, unlike storage device 1735, the system memory is avolatile read-and-write memory, such a random access memory. The systemmemory 1725 stores some of the instructions and data that the processorneeds at runtime. In some embodiments, the invention's processes arestored in the system memory 1725, the permanent storage device 1735,and/or the read-only memory 1730. From these various memory units, theprocessing unit(s) 1710 retrieve instructions to execute and data toprocess in order to execute the processes of some embodiments.

The bus 1705 also connects to the input and output devices 1740 and1745. The input devices 1740 enable the user to communicate informationand select commands to the electronic system. The input devices 1740include alphanumeric keyboards and pointing devices (also called “cursorcontrol devices”). The output devices 1745 display images generated bythe electronic system 1700. The output devices 1745 include printers anddisplay devices, such as cathode ray tubes (CRT) or liquid crystaldisplays (LCD). Some embodiments include devices such as a touchscreenthat function as both input and output devices.

Finally, as shown in FIG. 17 , bus 1705 also couples electronic system1700 to a network 1765 through a network adapter (not shown). In thismanner, the computer can be a part of a network of computers (such as alocal area network (“LAN”), a wide area network (“WAN”), or an Intranet,or a network of networks, such as the Internet. Any or all components ofelectronic system 1700 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors,storage and memory that store computer program instructions in amachine-readable or computer-readable medium (alternatively referred toas computer-readable storage media, machine-readable media, ormachine-readable storage media). Some examples of such computer-readablemedia include RAM, ROM, read-only compact discs (CD-ROM), recordablecompact discs (CD-R), rewritable compact discs (CD-RW), read-onlydigital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a varietyof recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.),flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.),magnetic and/or solid state hard drives, read-only and recordableBlu-Ray® discs, ultra-density optical discs, any other optical ormagnetic media, and floppy disks. The computer-readable media may storea computer program that is executable by at least one processing unitand includes sets of instructions for performing various operations.Examples of computer programs or computer code include machine code,such as is produced by a compiler, and files including higher-level codethat are executed by a computer, an electronic component, or amicroprocessor using an interpreter.

While the above discussion primarily refers to microprocessor ormulti-core processors that execute software, some embodiments areperformed by one or more integrated circuits, such asapplication-specific integrated circuits (ASICs) or field-programmablegate arrays (FPGAs). In some embodiments, such integrated circuitsexecute instructions that are stored on the circuit itself.

As used in this specification, the terms “computer”, “server”,“processor”, and “memory” all refer to electronic or other technologicaldevices. These terms exclude people or groups of people. For thepurposes of the specification, the terms display or displaying meansdisplaying on an electronic device. As used in this specification, theterms “computer readable medium,” “computer readable media,” and“machine readable medium” are entirely restricted to tangible, physicalobjects that store information in a form that is readable by a computer.These terms exclude any wireless signals, wired download signals, andany other ephemeral signals.

This specification refers throughout to computational and networkenvironments that include virtual machines (VMs). However, virtualmachines are merely one example of data compute nodes (DCNs) or datacompute end nodes, also referred to as addressable nodes. DCNs mayinclude non-virtualized physical hosts, virtual machines, containersthat run on top of a host operating system without the need for ahypervisor or separate operating system, and hypervisor kernel networkinterface modules.

VMs, in some embodiments, operate with their own guest operating systemson a host using resources of the host virtualized by virtualizationsoftware (e.g., a hypervisor, virtual machine monitor, etc.). The tenant(i.e., the owner of the VM) can choose which applications to operate ontop of the guest operating system. Some containers, on the other hand,are constructs that run on top of a host operating system without theneed for a hypervisor or separate guest operating system. In someembodiments, the host operating system uses name spaces to isolate thecontainers from each other and therefore provides operating-system levelsegregation of the different groups of applications that operate withindifferent containers. This segregation is akin to the VM segregationthat is offered in hypervisor-virtualized environments that virtualizesystem hardware, and thus can be viewed as a form of virtualization thatisolates different groups of applications that operate in differentcontainers. Such containers are more lightweight than VMs.

Hypervisor kernel network interface modules, in some embodiments, arenon-VM DCNs that include a network stack with a hypervisor kernelnetwork interface and receive/transmit threads. One example of ahypervisor kernel network interface module is the vmknic module that ispart of the ESXi™ hypervisor of VMware, Inc.

It should be understood that while the specification refers to VMs, theexamples given could be any type of DCNs, including physical hosts, VMs,non-VM containers, and hypervisor kernel network interface modules. Infact, the example networks could include combinations of different typesof DCNs in some embodiments.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. For instance, several examples wereprovided above by reference to specific distribute storage processes,such as vSAN. One of ordinary skill will realize that other embodimentsuse other distributed storage services (e.g., vVol offered by VMware,Inc.). The vSAN and vVol services of some embodiments are furtherdescribed in U.S. Pat. Nos. 8,775,773 and 9,665,235, which are herebyincorporated by reference. Thus, one of ordinary skill in the art wouldunderstand that the invention is not to be limited by the foregoingillustrative details, but rather is to be defined by the appendedclaims.

We claim:
 1. A non-transitory machine readable medium storing a programfor providing a machine executing on a host computer access to anexternal storage through a network interface card (NIC) connected to abus of the host computer, the program for execution by at least oneprocessing unit of the NIC, the program comprising sets of instructionsfor: defining a physical function (PF) module to represent a port of theNIC to the machine executing on the host computer, said port for use toperform read/write operations to the external storage for the machine,said PF module for execution by at least one processing unit of the hostcomputer; defining a virtual function (VF) module to associate with thePF module and to execute with at least one processing unit of the NIC;configuring a virtual switch executing on the NIC to pass, to the VFmodule, packets from the external storage to the machine, and toreceive, from the VF module, packets from the machine to the externalstorage; passing storage access command packets from the machine to theexternal storage through the PF module, the bus, the VF module, and thevirtual switch; and passing storage access response packets from theexternal storage to the machine through the virtual switch, VF module,the bus and the PF module.
 2. The non-transitory machine readable mediumof claim 1, wherein the bus is a PCIe (peripheral component interconnectexpress) bus, and the PF module is a module defined through the PCIebus.
 3. The non-transitory machine readable medium of claim 1, whereinthe PF module refers to an interface of the NIC that is recognized as aunique resource of the NIC.
 4. The non-transitory machine readablemedium of claim 3, wherein the unique resource is a NIC that is exposedthrough the PF module that is created through the bus.
 5. Thenon-transitory machine readable medium of claim 1, wherein: the hostcomputer executes a device emulation module that presents a set of oneor more external storages as a local storage connected to the bus, themachine is a virtual machine (VM) executing on the host computer, andthe VM comprises a driver for accessing the local storage through thebus.
 6. The non-transitory machine readable medium of claim 5, whereinthe host computer further executes a distributed storage service thataccounts for the machine's lack of knowledge regarding the set ofexternal storages being used to emulate the local storage.
 7. Thenon-transitory machine readable medium of claim 5, wherein the hostcomputer further executes at least two network fabric storage driversand a driver-selecting module to select one of the two network fabricstorage drivers for each storage-access command.
 8. The non-transitorymachine readable medium of claim 1, wherein the set of instructions fordefining the VF module comprises sets of instructions for: configuringthe VF module to pass a first plurality of packets associated with thestorage-access commands to the virtual switch along a slowpacket-processing path when the VF module does not have forwarding rulesfor processing the first plurality of packets; configuring the VF moduleto pass a second plurality of packets associated with the storage accesscommands to a port of the NIC along a fast packet-processing path whenthe VF module has forwarding rules for processing the second pluralityof packets.
 9. The non-transitory machine readable medium of claim 8,wherein the virtual switch provides forwarding rules to the VF moduleafter processing packets along the slow path.
 10. The non-transitorymachine readable medium of claim 8, wherein the VF module provides atleast one packet in the second plurality of packets directly to a portof the NIC without going through a NIC driver executing on the NIC. 11.A method for providing a set of one or more processes executing on ahost computer access to an external storage through a network interfacecard (NIC) connected to a bus of the host computer, the methodcomprising: defining a physical function (PF) module to represent a portof the NIC to the set of processes, said port for use to performread/write operations to the external storage for the set of processes,said PF module for execution by at least one processing unit of the hostcomputer; defining a virtual function (VF) module to associate with thePF module and to execute with at least one processing unit of the NIC;passing storage access commands from the set of processes to theexternal storage through the PF module, the bus, and the VF module; andpassing storage access responses from the external storage to the set ofprocesses through the VF module, the bus and the PF module.
 12. Themethod of claim 11, wherein the bus is a PCIe (peripheral componentinterconnect express) bus, and the PF module is a module defined throughthe PCIe bus.
 13. The method of claim 11, wherein the PF module refersto an interface of the NIC that is recognized as a unique resource ofthe NIC.
 14. The method of claim 13, wherein the unique resource is aNIC that is exposed through the PF module that is created through thebus.
 15. The method of claim 11, wherein: the host computer executes adevice emulation module that presents a set of one or more externalstorages as a local storage connected to the bus, the set of processescomprises a virtual machine (VM) executing on the host computer, and theVM comprising a driver for accessing the local storage through the bus.16. The method of claim 15, wherein the host computer further executes adistributed storage service that accounts for the set of processes lackof knowledge regarding the set of external storages being used toemulate the local storage.
 17. The method of claim 15, wherein the hostcomputer further executes at least two network fabric storage driversand a driver-selecting module to select one of the two network fabricstorage drivers for each storage-access command.
 18. The method of claim11, wherein defining the VF module comprises: configuring the VF moduleto pass a first plurality of packets associated with the storage-accesscommands to a virtual switch along a slow packet-processing path whenthe VF module does not have forwarding rules for processing the firstplurality of packets; configuring the VF module to pass a secondplurality of packets associated with the storage access commands to aport of the NIC along a fast packet-processing path when the VF modulehas forwarding rules for processing the second plurality of packets. 19.The method of claim 18, wherein the virtual switch provides forwardingrules to the VF module after processing packets along the slow path. 20.The method of claim 18, wherein the VF module is a network acceleratorthat facilitates the forwarding of the packets related to the externalstorage.